Old twin Cam Engine and block

[Watership Down]

I have an engine and block here and I wonder if anyone can share any info on them. On the engine the number is LP7431LBA On the block there is no engine # (doesn't look as if there is anywhere to put one) cast into the block is 681 F 6015D

[billwill]

By "on the engine" I presume you mean on the back end of the cylinder head ? Or do you mean that you have a complete engine plus an extra spare block?

The engine number on the block, should be on the slightly sloping flat bit at the top of the right hand engine mount (I think). It usually needs a good clean to see it.

[Watership Down]

The spare block does not have anything above the engine mount at all. is there some other place on the block it could be although I have checked every where.

[billwill]

Dunno, I regret.

Could it be that it was never part of a completed engine and so never had an engine number stamped on it, or maybe it was never a Twin-Cam, but a different Ford engine and that they stamped only the head and did not stamp the block?